This invention relates generally to a device in which an electrical shock is delivered to the animal that comes into contact with it. Such devices find primary utility as pest deterrent devices. In particular, this invention pertains to such a device that is particularly well adapted for use as a bird deterrent device, but could be utilized with other animals as well.
Ever since electricity was first put to commercial and residential use in the United States in the late 1800's to solve the age-old problem of darkness, the ability of electrical current to deliver an electric shock to a person or animal has been recognized, and electricity utilized as a result for things other than powering lights and motors. Non-lethal applications of electricity for use in encouraging animals to do something or not do something soon followed the use of electricity for lights and motors. The electric cattle prod is perhaps the best known of those devices. Today, however, electricity is used in many ways with animals, such as electric fences to keep farm animals in and predators out, and even dog trainers sometime use an electrical stimulus in a dog collar to assist in their training.
Another age-old problem that has been perplexing mankind since long before the discovery and harnessing of electricity is the propensity of pests in general, but particularly birds, to land in areas where their human neighbors would prefer they didn't. Since the very first bird deterrent device used by man—undoubtedly a thrown rock—an incredible array of devices have been used to dissuade birds from landing or roosting in areas desired by the birds but undesirable to humans. Metallic spike-like, coil or rotating devices, sound-emitting devices, imitation predators, and even real predators, are just a few examples of bird deterrent devices that have been used. Therefore, it is not at all surprising that devices using lethal and non-lethal electrical shock would also be employed along the way.
A typical device of this type is shown in U.S. Pat. No. 4,299,048, in one embodiment of which a pair of copper wires connected to a power source are embedded in opposites sides of a cable of appropriate diameter such that when the birds of choice (in this case, starlings) land on the cable, their feet touch both wires, closing the circuit and thereby delivering a lethal shock to the birds.
The much more recently-issued U.S. Pat. No. 6,283,064 discloses another version of a bird and pest deterrent device in which a pair of crimped copper wires are appropriately spaced apart so that the bird's or other pest's feet will touch both wires, resulting in a short circuit and delivering a shock to the bird or other pest.
Other devices for carrying electric charges for discouraging birds and other pests are described in U.S. Pat. Nos. 3,294,893; 3,336,854; 3,717,802; 4,299,048; and 5,850,808, for example. Each of these necessarily include the broad concept of appropriately spaced-apart wires which will both be contacted by the bird (or other pest's) feet (or other part of their anatomy) so as to deliver the appropriate electric shock.
While all of these devices work, at least initially, to an acceptable degree in some installations, the problem that prior art devices of this type have long encountered has been in providing such a device that can be used in something other than relatively straight-line, flat applications and that have a sufficiently long expected useful life in that application. These problems arise from the fact that these devices inherently need two things—1) the conductive elements, typically metal wires, that carry the electrical current; and 2) a non-conductive base element, to which the wires are attached. Most typically, the metal wires are held by friction and/or glue within an appropriately sized channel in the base. See, for example, the devices disclosed in U.S. Pat. Nos. 5,850,808; 4,299,048 and 3,366,854. Because the metal wires and the non-metallic bases have different coefficients of expansion and contraction, and different degrees of flexibility, however, there is a tendency for the wires in these devices to become detached from the base over time since these devices are typically used in locations that are directly exposed to the weather. This problem is exacerbated if the location to which the device is applied is other than a straight, flat surface, as any twisting or bending of the device places unequal stresses on the base and the wires causing them to become loose or even pop out of their holding channels.
These two problems have been addressed in different ways, and continue to cause problems in the industry, as those skilled in the art continue to seek to find ways to solve the problems. For one recent example, in U.S. Pat. No. 6,283,064, the base “has spaced notches along each edge to provide flexibility to the base, whereby the base may be bent both out of the plane and within the plane” (id., Col. 1, lines 64-66) and the “wires are crimped in undulating fashion along their length, to provide them with give so that they will not disassociate from the base when it is bent or when the wires and base expand and contract at different rates.” (Id., Col. 2, lines 7-11).
While the prior art devices are useful to a degree, they still suffer from certain drawbacks, including limitations on the degree to which they can be bent without inducing potentially disabling stresses, and relatively higher cost. Therefore, there exists a need in the art for an improved electrical shock deterrent device that solves these problems, and does so in an efficient, reliable, low cost way.